The present invention relates to the field of blood pressure and more particularly to an apparatus and method for safely reducing the resting blood pressure (both systolic and diastolic pressures) of humans and especially for those humans who are hypertensive.
Buck, et at., "Isometric Occupational Exercise and the Incidence of Hypertension", J. Occup. Med., 27:370-372, 1985, show a practical application of the principle of isometric exercise influencing blood pressure. The incidence of hypertension was lower in individuals engaged in occupations that had higher components of isometric efforts. A subtle, but significant, feature of this paper is that the original hypothesis was that, since blood pressure rises during an isometric effort, a job that required repeated isometric efforts might have an accumulative effect and contribute to a sustained elevation of blood pressure. However, the investigation reported showed just the opposite result.
Choquette, et al., "Blood Pressure Reduction in `Borderline` Hypertensives Following Physical Training", Can. Med. Assoc. J., 1108:699-703, 1973, show a comparison between rhythmic and isometric exercise. While these authors showed an effect of exercise on lowering resting blood pressure, the present invention which utilizes isometric exercise lowers the blood pressure even more. Further, it has been well documented that compliance (staying with the treatment) is rather poor for rhythmic exercise. A greater percentage of people who run, jog, cycle, swim, or the like, to achieve fitness, simply quit.
Clarke, et al., "The Duration of Sustained Contractions of the Human Forearm at Different Muscle Temperatures", J. Physiol., 143:454-473, 1958, show an early hand grip dynamometer which is used by patients whose arms are immersed in water for measuring the duration of sustained contractions of the human form at different muscle temperatures.
Gilders, et al., "Endurance Training and Blood Pressure in Normotensive and Hypertensive Adults", Med. Sci. Sports. Exerc., 21:629-636, 1989, report a study that indicates that endurance training of the rhythmic or aerobic type does not have the benefit of lowering blood pressure, for either subjects starting with normal or with hypertensive blood pressures.
Hagberg, et al., "Effective Weight Training on Blood Pressure and Hemodynamics in Hypertensive Adolescents", J. Pediatr., 1104:147-151, 1984, show that weightlifting, which has a major isometric component, although not a "pure" isometric effort, can keep blood pressure down after it was lowered by rhythmic training.
Harris, et al., "Physiological Response to Circuit Weight Training in Borderline Hypertensive Subjects", Med. Sci. Spots Exerc., 19:246-252, 1987, and Hurley, et at., "Resistive Training Can Induce Coronary Risk Factors Without Altering VO.sub.2max or Percent Body Fat", Med. Sci. Sports Exerc., 20:150-154, 1988, both deal with resistive training similar to the Hagberg, et al., publication in which there is movement, hence rhythmic effort, but where much weight is being moved, hence, "resistive" effort. This is interpreted to mean that in such a "mixed" effort, with both rhythmic and isometric components, that the isometric component is providing the real benefit in lowering resting blood pressure. In both of these papers, VO.sub.2max does not change. The measure of change of VO.sub.2max is one associated with improvement of endurance seen with rhythmic exercise. The point, then, supports contentions about isometric exercise in that resistive efforts which have a major isometric component, do not show the kind of change in VO.sub.2max seen typically with rhythmic or endurance exercise, yet do show the kind of lowering of resting blood pressure, though not as much, as can be obtained with only isometric exercise.
It has been reported that a reduction in blood pressure reduces the incidence of mortality in the report, Hypertension Detection and Follow-up Program Cooperative Group, "The Effect of Treatment on Mortality in `Mild` Hypertension", N. Engl. J. Med., 307:976-980, 1982. In an early paper, Kiveloff, et al., "Brief Maximal Isometric Exercise in Hypertension, J. Am. Geriatr. Soc., 9:1006-1012, 1971, suggest that isometric exercise can lower blood pressure in humans. No device was used in which to perform the isometric effort, rather subjects just stood and contracted muscles of the body. No quantitative measure of the amount of isometric effort is reported. Merideth, et al., "Exercise Training Lowers Resting Renal but not Cardiac Sympathetic Activity in Humans", Hypertension, 18:575-582, 1991, present evidence that rhythmic exercise results in a reduction of peripheral resistance, i.e., a "relaxation" of blood vessels in the body, which would result in the lowering of blood pressure within them.
Seals and Hagberg, "The Effect of Exercise Training on Human Hypertension: A Review", Med. Sci. Sports Exerc., 16:207-215, 1984, reviews 12 earlier investigations of rhythmic exercise studies.
Tipton, "Exercise, Training and Hypertension: An Update", Exerc. Sport Sci., Rev., vol. 19, Ch. 13, 1991, pp 447-505, is one of the most comprehensive recent reviews of the state of the art on the effect of exercise on blood pressure. At page 473, Tipton refers to a study which included "circuit training" which has a significant isometric component and which showed a lowering of blood pressure. The author also refers to one of his own studies with rats which were made to perform a type of isometric exercise in which the rats "unexpectedly" did not experience an increase in blood pressure as the authors had predicted would happen.
Thus, the art makes clear that a lowering of resting blood pressure is beneficial to humans in general and is particularly important to those humans who are hypertensive. While isometric and rhythmic (or dynamic) exercise is beneficial to humans in general, the isometric component of exercise, according to the foregoing art, appears to contribute more significantly to the lowering of resting blood pressure. The present invention indeed confirms such speculation in the art by disclosing an apparatus and isometric method for safely reducing the resting blood pressure of humans. The present invention has been reported in "Isometric Exercise Training Lowers Resting Blood Pressure", Med. Sci. Sports Exerc., 24 (7):749-754, 1992. The disclosure of all of the foregoing publications are expressly incorporated herein by reference.